Tonalite

Tonalite is an igneous, plutonic (intrusive) rock, of felsic composition, with phaneritic (coarse-grained) texture.

Quartz (SiO2) is present as more than 20% of the total quartz-alkali feldspar-plagioclase-feldspathoid (QAPF) content of the rock.

[1][2] Amphiboles and biotite are common in lesser quantities, while accessory minerals include apatite, magnetite and zircon.

[6] Trondhjemite is an orthoclase-deficient variety of sodium-rich tonalite with minor biotite as the only mafic mineral, named after Norway's third largest city, Trondheim.

[7] Tonalites, together with granodiorites, are characteristic of calc-alkaline batholiths formed above subduction zones.

A piece of tonalite on red granite gneiss from Tjörn, Sweden
QAPF diagram with tonalite field highlighted
Roc de la Calme (or Calma), a tonalite tor in the Mont-Louis-Andorra granite pluton (Variscan Pyrenees). [ 9 ] [ 10 ]